Research On Human-induced Vibration Of Pedestrian Suspension Bridge Based On MSD Model

With the development of high-strength materials,the improvement of construction level and the improvement of people’s aesthetic requirements,the design of pedestrian bridges is becoming more and more gentle,accompanied by the prominent problem of human-induced vibration.The traditional forced vibration research method is no longer suitable for accurate structural vibration response calculation.Therefore,clarifying the interaction relationship between pedestrians and bridges and establishing corresponding pedestrian models have become the key.In this paper,combined with theoretical analysis,numerical simulation and experimental testing methods,the pedestrian load,the dynamic characteristics of the simply supported beam and pedestrian bridge coupling system,and the suspended pedestrian bridge coupling numerical simulation are studied.The research results can provide the application basis and theoretical basis for the coupled dynamic analysis of pedestrians and bridges.The main work and innovative research results of this paper are briefly described as follows:(1)The load model and MSD(mass-spring-damper)model are summarized.Analyzing the existing pedestrian load,based on the reference to the German EN03 and the British BS5400 code,the load form to be used in this article is summarized and compared.At the same time,it summarized and analyzed the single-person overall MSD model,single-person bipedal MSD model,running MSD model and crowd MSD model and their respective characteristics.(2)Analyze the vertical coupled vibration of the pedestrian simply supported beam.In this chapter,first theoretically derive the formulas of the forced action and the interaction relationship of the bridge,and obtain the dynamic response equation of the forced vibration and the dynamic balance equation of the interaction.And use MATLAB to solve the simply supported beam and compare the two models.The MSD model coupling system parameters are analyzed,and it is found that as the pedestrian moves,the coupling fundamental frequency of the system first decreases and then increases,and it is the smallest when the pedestrian moves to the middle of the span.The damping presents a trend of first increasing and then decreasing,with the largest mid-span.Finally,based on the single-person overall MSD model,the single-person and biped MSD model and the running MSD model were compared.(3)Apply several models to the built pedestrian suspension bridge,and use ANSYS to carry out finite element analysis.The difference in vibration response of several models on flexible pedestrian suspension bridges is compared.The impact of different pedestrian paths,pedestrian speeds and number of pedestrians on the vibration response is explored.(4)The vibration characteristic test and human-induced vibration test of pedestrian suspension bridge were carried out.The vibration mode of the suspension bridge is obtained through the vibration characteristic test and compared with the finite element analysis.Then,walking and running tests were carried out on the pedestrian suspension bridge,and the load model,MSD model and experimental results were compared.It was proved that the MSD model was closer to the measured value than the load model,and the pedestrian load had multiple levels of expression.It also explored the changes in the number of pedestrians and the changes in the form of pedestrian movement resulting in changes in the vibration response.It was found that the increase in the number of pedestrians and running will increase the vibration response.When the step frequency is the same,the frequency of the maximum vibration response of running is greater than that of walking.